The long-term goal of this proposal is to increase understanding of taste recognition and taste perception. The gustatory system of Drosophila provides an excellent model for studies of taste recognition because it is associated with well-defined chemical cues, robust behavioral responses and a complex nervous system that is amenable to molecular, genetic and electrophysiological approaches. Taste recognition in Drosophila is mediated by gustatory neurons on the proboscis, internal mouthparts, legs, wings and ovipositor. Recent studies have identified three taste cell populations in the fly: sugar-, bitter-, and carbon dioxide-sensing cells. The proposed studies expand on this work, with the aim of identifying molecular mechanisms underlying the detection of specific tastes. In mammals, G protein-coupled receptors mediate detection of sugars, amino acids, and bitter compounds, whereas ion channels detect salts and acids. In Drosophila, a large family of candidate gustatory receptor genes is expressed in sugar and bitter-sensing cells and is likely to mediate detection of these tastes. However, the molecular mechanisms underlying the detection of other tastes are not established. In preliminary studies, microarray analyses, combined with in situ hybridization and transgenic experiments, identified novel taste-specific molecules. The proposed experiments are designed to determine the function of these taste-specific molecules with the aim of increasing understanding of taste recognition in the periphery. PUBLIC HEALTH RELEVANCE: This research focuses on the molecular mechanisms of taste detection in insects. Elucidating the molecular mechanisms underlying detection of chemical compounds by Drosophila gustatory neurons will provide basic insight into chemical detection by insects. Insect carriers of human disease use chemical recognition to target their human hosts and are responsible for the spread of devastating diseases such as malaria, typhoid, cholera and trachoma. Defining the molecular mechanisms of chemical detection in the model organism Drosophila is essential in order to identify homologues in disease-carrying insects, a necessary first step toward identifying receptor antagonists to manipulate host recognition. In addition, identifying taste receptors in Drosophila will suggest candidate molecules that may participate in taste detection in humans.